1. Field of Invention
The present invention relates to a radio communication transceiver, and more particularly to an impedance matching circuit used for the radio communication transceiver.
2. Related Art
When a radio communication transceiver is applied, impedance matching between the transceiver and an antenna needs to be taken into consideration. In the radio communication transceiver of the prior art, a used amplifier is in a dual-end transmitting manner, which relatively increases energy consumption, and also increases cost consumption.
For example, in the US application with the public No. 2007/0152904 A1 and entitled “IMPEDANCE MATCHED PASSIVE RADIO FREQUENCY TRANSMIT/RECEIVE SWITCH”, ratio turns in a selected balun transformer is utilized, and is used together with a primary winding connected to an antenna and with a power amplifier (PA) and a low noise amplifier (LNA) in dual-end transmitting connected to a secondary winding, which results in the impedance matching for the antenna at the time of outputting and inputting respectively.
Further for example, in the US application with the public No. US 2004/0253939A1 and entitled “INTEGRATED CIRCUIT RADIO FRONT-END ARCHITECTURE AND APPLICATIONS THEREOF”, a multi-tap balun transformer consisting of a primary winding and a symmetrical multi-tap secondary winding is utilized, and an input matching circuit is added between the primary winding and an antenna, a PA and an LNA in dual-end transmitting of which are connected to a first pair and a second pair of the symmetrical multi-tap secondary winding respectively. By switching a mode of the multi-tap balun transformer, impedance matching for the antenna at the time of outputting and inputting is achieved respectively.
However, both of the foregoing applications are used together with the amplifiers in the dual-end transmitting manner, which relatively increases energy and loss consumption. Hence, it is expected to invent a radio communication transceiver, in which a single transformer is used together with an LNA in single end transmitting manner, so as to reduce energy consumption, and achieve impedance matching simultaneously without any additional elements, thus decreasing the cost.